Merge "docs: Quick update to multi-window page" into mnc-mr-docs

</p>

<p>

  If the user is resizes a window and makes it larger in either dimension,

  the system fills in the expanded

  area with the color specified by the {@link android.R.attr#windowBackground

  windowBackground} attribute, or by the default

  <code>windowBackgroundFallback</code> style attribute. When the user finishes

  resizing the window, the activity is redrawn with its new dimensions, as

  described in <a href=

  "{@docRoot}guide/topics/resources/runtime-changes.html">Handling Runtime

  Changes</a>.

  If the user is resizing a window and makes it larger in either dimension, the

  system resizes the activity to match the user action and issues <a href=

  "{@docRoot}guide/topics/resources/runtime-changes.html">runtime changes</a>

  as needed. If the app lags behind in drawing in newly-exposed areas, the

  system temporarily fills those areas with the color specified by the {@link

  android.R.attr#windowBackground windowBackground} attribute or by the default

  <code>windowBackgroundFallback</code> style attribute.

</p>

<h2 id="configuring">Configuring Your App for Multi-Window Mode</h2>